Pedregon Corporation has provided the following information:

Cost per UnitCost per PeriodDirect materials$6.95Direct labor$3.50Variable manufacturing overhead$1.75Fixed manufacturing overhead$19,800Sales commissions$0.40Variable administrative expense$0.50Fixed selling and administrative expense$7,700

If the selling price is $21.30 per unit, the contribution margin per unit sold is closest to:

a. 4.20

b8.20

c. 10.85

d. 3.80